Improvement in electrical indicators for letter-boxes



".3. DAVID.. Electrical-Indicator for Letter-Boxes.

101591083 Patntedlan..26,1875..

A 7///II/III//I//III/IIIIIIIIIII/IIIIIIII UNITED STATES PATENT QFFICE.

HENRY R. DAVID, OF NEW YORK, N. r.

IMPROVEMENT IN ELECTRICAL INDICATORS FOR LETTER-BOXES.

Specification forming'part of Letters Patent No. 159,083, dated January 26, 1875; application filed September 23, 1874. w

- ters, and the ofiice of the person for whom the letters are intended is frequently at a distance,

or upon one of the upper floors.

The object of the present invention is to indicate at the distant room whenever a letter is placed in the reception-box by the postman or other person. In the drawing, Figure 1 is an elevation, and Fig. 2 is ayertical section, of the improved letter-box, with the circuits to a distant station.

Within the box 0 is a receiving-plate, a, upon which the letter falls when dropped in through the opening I) in the box. This plate a swings upon the bearings 70, and is balanced by a removable counterpoise, f. One wire of the battery 'i is connected with k, and the other with the circuit-closer e, and in this circuit an electro-magnet is placed to operate a hell or other alarm or indicator.

"The circuit-closer a may be an arm upon the plate a, that swings with it, and comes intocontact with a stop.

When a letter is dropped into the box its weight moves the plate a, and closes the circuit. Hence an alarm can be given at the oflice or distant place, so that the letter can be obtained from the box.

The diagram, Fig. 3, illustrates the manner of arranging the circuits so that several boxes and their corresponding alarm bells may be operated from one battery, and only the proper alarm will be rung, because the alarm and its box are in branch circuits from the main circuit.

The electric circuit, connections, and alarm may be arranged so that the circuit remains closed except when broken by the movement of the platform. In that case the alarm or signal will be given by breaking the circuit.

I claim as my invention- The letter receptacle or box provided with a balanced platform that is moved. by the Weight of a letter, in combination with a circuit-closer and connections to a distant'alarm or indicating apparatus, substantially as set forth.

Signed by me this 21st day of September, 187 4.

' HENRY R. DAVID.

lWitnesses:

CHAS. H. SMITH, GEO. T. PINCKNEY. 

